1. Field of the Invention
This invention relates to a punching and scoring tool for production of scored punched parts.
2. Description of the Related Art
Cardboard folding box blanks are usually provided with scores, which give the folding boxes their defined shape when they are subsequently erected. The contours as well as necessary incisions in the folding box blank are produced by punching. Manufacture is by strip steel punching and scoring tools on flat-bed or rotary punches.
The strip steel punching and scoring tools usually consist of a carrier board made e.g. from wood, composites of plastics with glass fabric or reinforced with metal plates in sandwich construction. Slots to receive punching or scoring rules are provided in these carrier boards according to the box contours. The punching rules project exactly as far as or further than the scoring rules from the carrier board. The punching rules operate against a punching/scoring plate made in most instances from steel.
Such tools are described for example, in patents DE 39 28 916 C1 or DE 38 31 393.
The scoring rules produce a scoring ridge in the folding box material by forcing the latter into a scoring groove. These scoring grooves can be cut into the punching/scoring plate or mounted as an attachment on the punching/scoring plate. The folding box material should be foldable accurately and with a defined folding resistance along the scores. The folding process is particularly important in automatic cartoning machines, because the attainable operating speed of the automatic cartoning machines depends on the accuracy and folding behaviour of the scores.
Problems in the production of accurate scoring rules result from the interaction of scoring rules and the scoring groove in the case of the already known steel strip punching and scoring tools. The scoring rule is an integral part of the carrier board, whereas the scoring grooves are mounted on the punching/scoring plate. The slots to receive the scoring rules are cut into the carrier board, e.g. with a numerically controlled laser. With the same program the scoring grooves are cut into the punching/scoring plate with numerical control. When aligning the carrier board with the punching/scoring plate it is nevertheless impossible to prevent the scoring rules in the carrier board not always being accurately centred with the associated scoring groove. This is unavoidable, because the scoring rules are held in the slots in the carrier board by a clamp fit. Consequently lateral stresses, which result in slight displacements, occur in the case of a large number of parallel scoring rules. The scoring rules must therefore be re-adjusted by hand or the scoring groove widths must be adapted accordingly. However, this is unfavourable, because the narrowest possible score is required to achieve an accurate and symmetrical folding edge.